1. Field of the Invention
The present invention relates to a frequency selective modulating apparatus and method using a re-spreading code and, more particularly, to a technique that uses a limited frequency band in which the strength of a signal transmitted by using a human body as a waveguide is greater than that of a signal radiated to the outside of the human body, avoiding a frequency band in which noise power around the human body is concentrated compared with other ranges, and allows for the free shifting of a transmission frequency band through re-spreading of a frequency selective baseband.
2. Description of the Related Art
Korean Patent No. 912543 entitled “Modulation and Demodulation Method and Apparatus using Frequency Selective Baseband” which was filed in 2007 and registered in 2009 by the inventor of the present invention discloses a technique that uses a limited frequency band to implement a human body communication system and transmits data at a frequency selective baseband by using multi-structured frequency selective spreading codes in order to transmit a larger amount of data through the limited frequency band.
However, the preceding patent in which data is transmitted only at a frequency selective baseband within a limited frequency band is disadvantageous in that the selective use of spreading codes degrades efficiency, and the free shifting of a transmission frequency band is not possible.